Such a sensor assembly is known from European patent application EP-A-0 330 632, which describes a device for measuring the steering angle operatively associated with the articulation between one of the rotary journals of one of the steered wheels and the body of the axle. A transducer is positioned parallel to the axis of the journal and a feeler co-operates with a stationary cam member having projections at certain angular positions. Also, an embodiment is shown in which a potentiometer is positioned in an axial recess of the King-pin of the journal. The shaft of the potentiometer is coupled to a fixation point on the axle body.
These known sensor assemblies provide a number of disadvantages. The sensors are mounted predominantly externally, thus being exposed to the environment. This results in a sensor system which is not robust and susceptible to failure through many mechanisms, such as accumulating dirt. This results in an unreliable operation of the sensor.
When a sensor in the form of a potentiometer is integrated inside a cavity in the King-pin, this will affect the mechanical strength of the King-pin. Also, potentiometer sensors will always need a fixation point to the rotating part, e.g. using a shaft coupling. In certain configurations, such a fixation point is not available, e.g. when the King-pin is designed to run through all of the spindle. Potentiometers used as position sensors also often have the disadvantage that they wear out easily, especially in the middle position.